^ 


HXdo0 11819  f^ :  ^^*-^^    Lm>^^^l^'  ..^c^^^cMi    Y  .^ 


The  Significance  of  Muscular  Variations, 

Illustrated  by  Reversions  of  the 

Anti-Brachial  Flexor  Group. 


By  GEO.  S.  HUNTINGTON. 


[Trans.  N.  Y.  Acad.  Sci.,  Vol.  XIV.  (Aug.  28,  1S95)  231-259.] 


Digitized  by  tine  Internet  Arciiive 

in  2010  witii  funding  from 

Open  Knowledge  Commons  (for  the  Medical  Heritage  Library  project) 


http://www.archive.org/details/significanceofmuOOhunt 


THE   SIGNIFICANCE    OF   MUSCULAR   VARIATIONS, 

ILLUSTRATED  BY.  REVERSIONS  OF  THE 

ANTI-BRACHIAL  FLEXOR  GROUP. 

By  Geo.  S.  Huntington. 

Read  by  Title,  Feb.  11, 1895. 

The  study  of  muscular  variations,  if  carried  on  systematically, 
embracing  observations  made  on  a  large  number  of  subjects, 
cannot  fail  to  reveal  certain  finer  differentious,  which,  while  lost 
in  a  mere  enumerative  record  of  muscle  variations,  gain  a  new 
and  important  significance  when  grouped  together  and  com- 
pared in  an  eflfort  to  trace  the  morphological  meaning  of  the 
variant  condition.  This  becomes  most  strikingly  apparent  in 
the  case  of  certain  appendicular  muscles,  and  especially  of  some 
muscles  of  the  fore-limb.  The  extreme  modifications  which,  in 
vertebrates  possessing  an  anterior  extremity,  widely  diflferent 
functional  requirements  have  impressed  on  this  portion  of  the 
locomotoiy  apparatus,  may  properly  be  held  responsible  for  the 
fact  that  here  variations  of  the  most  composite  t^^pe  are  to  be 
encountered.  A  glance  at  the  divergent  forms  presented  by  the 
vertebrate  pectoral  girdle  will  convince  us  that  the  muscular 
structures  connected  with  the  same  must  offer  deviations  from 
the  primitive  types,  which  not  onlj^  change  the  arrangement  of 
homologous  muscles  in  different  forms,  but  which  will  afford 
the  opportunity  for  numerous  reversions  to  the  original  con- 
dition in  the  case  of  any  individual  muscle. 

The  specialization  of  the  fore-limb,  in  exchanging  a  purely  or 
chiefly  locomotory  function  for  one  which  includes  or  substitutes 
the  prehensile  function,  and  the  consequent  higher  development 
of  the  manus,  has  more  especially  served  to  single  out  the  anti- 
brachial  flexor  group,  and  to  add  to  the  function  of  flexing  the 
forearm  at  the  elbow-joint  the  more  complicated  movements  of 
radial  rotation  in  supination  of  the  hand.  In  some  instances 
this  additional  functional  requirement  has  sufficed  to  specialize 
certain  members  of  the  flexor  group  as  supinators,  modifying 
the  insertion  so  as  to  restrict  the  same  chiefly  or  entirely  to  the 
radius,  and  separating  a  portion  of  the  flexor  mass  by  complete 
cleavage  from  adjoining  muscular  strata. 

This  is  most  excellently  seen  in  the  so-called  Biceps  flexor 
cubiti  of  Man  and  Primates  generally,  a  muscle  which  acts  as 


PVlU"  /'Jt 


•23"2  TRANSACTIONS   OF   THE  [MAY  13, 

one  of  the  chief  radial  supinators,  while  its  flexor  function  is  to 
a  considerable  extent  subordinated  to  this  main  action. 

In  muscles  of  this  type  variations  are  frequently  encoun- 
tered, many  of  them  being  reversional  in  character  and  pointing 
to  previ.Q.ns  ancestral  types  of  myotectiire. 

The  definition,  which  certain  muscular  attachments  obtain  by 
specialization  of  function,  is  accompanied  by  the  concomitant 
reduction  or  elimination  of  other  connections  which  have  lost 
their  original  value  and  significance  in  the  new  sphere  of  the 
muscle,  or  would  even,  if  retained,  interfere  with  the  same. 

The  muscle,  in  returning  in  an  incomplete  form  to  these  ob- 
solete conditions,  presents  reversions  to  which  many  of  the  ob- 
served variations  may  properly  be  ascribed. 

No  muscle  presents  these  features  more  strongl}'  developed 
than  the  Biceps  flexor  cubiti.  The  muscle  is,  next  to  the  Pal- 
maris  longus,  the  most  variable  in  the  body,  Macalister*  in 
his  Catalogue  of  Muscular  Anomalies  enumerating  no  less  than 
45  separate  variations. 

It  is  our  purpose  in  the  present  paper  to  discuss  only  a  cer- 
tain group  of  these  variations,  and  to  endeavor  to  obtain  an  in- 
sight into  their  significance. 

The  human  material,  on  which  the  following  observations 
have  been  made,  consists  of  464  upper  extremities  dissected 
during  the  year  1893  to  1894  in  the  Anatomical  Laboratory  of 
Columbia  College. 

As  the  explanation  of  the  probable  derivation  and  significance 
of  certain  of  these  variations  of  the  Biceps  muscle  is  closely  con- 
nected with  the  morphology  of  the  remaining  antibrachial  flexor 
group,  it  will  be  desirable  to  take  a  general  view  of  the  ar- 
rangement of  this  group,  before  proceeding  to  the  details. 

In  the  lowest  vertebrates  a  continuous  and  non-segmented 
plane  of  muscular  fibres  proceeds  from  the  ventral  aspect  of  the 
trunk  to  the  flexor  surface  of  the  anterior  limb.  This  condition 
is  best  represented  b}-  the  muscular  apparatus  of  the  pectoral  fin 
in  fishes. 

In  ascending  the  scale  differentiation  leads  to  the  more  or  less 
complete  separation  of  this  muscular  mass  into  layers  and  strata, 
which  may  or  ma}-  not  preserve  connections  with  each  other,  in- 
dicative of  their  original  union. 

A  consideration  of  the  general  arrangement  of  the  flexors  of  the 
forearm  in  higher  vertebrates  reveals  the  existence  of  three  main 
divisions  or  laj-ers,^  more  or  less  blended  with  each  other. 

♦Alexander  Maealister.  Additional  Observations  on  Muscular  Anomalies  in  Human 
Anatomy  (III.  Series),  with  a  Catalogue  of  the  Principal  Muscular  Variations  hitherto 
published.    Transact,  of  the  Royal  Irish  Academy,  Vol.  XXV.,  Pt.  I.,  Dublin,  1872. 

t  G.  M.  Humphry,  Obser\-ations  in  Myology,  Cambridge  and  London,  1872,  p.  163. 


1895.]  NEW    YORK    ACADEMY    OP    SCIENCES.  233- 

1.  Superficial  layer,  a  portion  of  the  superficial  ventro-ap- 
pendieular  muscular  sheet,  reaching,  usually  by  combination 
with  the  succeeding  layer,  a  skeletal  or  fascial  insertion  in  the 
forearm.  Usuall}^  but  few  and  unimportant  traces  of  this  la3' er 
are  found  in  higher  forms,  the  great  bulk  of  the  superficial  fibres 
passing  from  the  trunk  to  the  anterior  extremity  terminating,  as 
Pectoralis  Maj or  and  Latissimus  dorsi,  respectively  on  the  radial 
and  ulnar  margin  of  the  humerus.  Occasionally,  however,  the 
Pectoralis  Major  is  not  arrested  at  the  radial  tubercle  of  the 
humerus,  but,  as  in  Orycteropus,  accompanies  the  Biceps  to  the 
radius,  or,  as  in  the  Otter  and  Wildcat,  together  with  some 
fibres  of  the  Trapezio-Deltoid,  accompanies  the  Brachialis  anticus 
to  the  ulna,  or,  as  in  the  Seal,  expands  into  the  fascia  of  the  fore- 
arm and  thus  reaches  the  hand.* 

2.  Intermediate  layer,  constituting  the  "  extrinsic "  limb 
muscles  of  Humphry,  derived  from  the  deeper  portion  of  the 
ventro-appendicular  sheet,  forming  muscles  arising  from  the 
pectoral  girdle  and  passing  over  the  elbow  to  the  bones  of  the 
forearm.  This  group  is  represented  by  the  Biceps,  which 
muscle,  besides  its  relation  to  the  Coraco-humerals,  presently  to 
be  considered,  presents  various  degrees  of  continuity  with,  and 
separation  from,  the  following  layer. 

3.  Deep  layer,  formed  by  the  "intrinsic  "  limb  muscles,  aris- 
ing from  the  humerus,  and  pursuing  the  same  course  as  the  2nd 
layer,  represented  by  the  Brachialis  anticus,  or  in  some  in- 
stances (Hippopatamus)  by  the  Brachio-radialisf ,  which  mus- 
cle in  this  animal  is  larger  and  occupies  the  space  on  the  outer 
side  of  the  humerus  from  which  the  Brachialis  anticus  usually 
arises. 

Here  we  meet  with  a  replacement  of  the  usual  Brachio-ulnar 
by  a  Brachio-radial  flexor,  to  the  complete  exclusion  of  the 
former. 

The  2d  and  3d  laj^ers,  i.  e.,  Biceps  and  Brachialis  anticus, 
either  considered  by  themselves,  or  more  especially  when  viewed 
in  the  light  of  their  mutual  relation,  present  many  points  of 
morphological  interest,  and  suggest  explanations  of  human  re- 
visional  variations  of  the  former  muscle. 

A  general  review  of  the  conditions  found  in  the  anti-brachial 
flexor  graup  will  call  for  the  consideration  of  the  following 
points  : 

I.  Morphology  of  the  Bicep)S,  the  variations  of  the  muscle  and 
their  significance. 

*  Humphry,  op.  cit.,  p.  147. 
t  Humphry,  op.  cit.,  p.  163. 


234  TRANvSACTIONS   OF    THE  [MAY  13, 

II.  Relations  of  Biceps  to  the  adjoining  deep  ventro-ap)pendic- 
vlar  muscles, viz.:  the  Goraco-humerals. 

Ill  Relations  of  Biceps  to  the  deep  intrinsic  flexor  of  the 
forearm,  viz.:  the  Brachialus  anticus. 

I.  Morphology  of  the  Biceps  Flexor  Cubiti. 

We  may  in  the  first  place  consider  the  composition  of  the 
human  Biceps  in  the  light  derived  from  the  comparative  study 
of  the  muscle  in  other  vertebrates. 

Although  our  knowledge  of  comparative  myolog\'  is  still 
somewhat  meagre,  considering  the  extent  of  the  subject,  and  al- 
though the  results  of  investigations  appear  at  times  too  frag- 
mentary and  uncertain,  yet  enough  is  known  to  justify  us  in 
regarding  the  form  in  which  the  Biceps  usually  presents  itself  in 
man  as  the  result  of  certain  specializations  of  function  acquired 
by  the  upper  extremity,  which  have  brought  about  a  greater  de- 
finition of  certain  portions,  whereas  other  parts,  lacking  the 
stimulus  of  this  functional  requirement,  have  retrograded  and 
have  become  to  a  great  extent  rudimentar}-  or  entirelj'  elimin- 
ated. 

A.  Origin. 

In  the  complete  form  the  Biceps  occupies  two  points  of  origin 
from  the  shoulder-girdle  corresponding  to  the  anterior  edge  of 
the  glenoid  socket  and  to  the  coracoid  element. 

The  actual  arrangement  of  the  muscle  in  individual  forms 
will  be  naturally  greatly  influenced  by  the  structure  of  the 
girdle,  and  notably  by  the  predominance  or  reduction  of  the 
coracoid  and  its  appendages.  An  instance  of  this  is  afforded 
b}'  the  extensive  Coraco-radial  muscle  which  represents  the 
Biceps  in  Cryptobranchus  japonicus,  whereas,  in  man}'  other 
forms,  the  coracoid  origin  of  the  muscle  is  much  reduced  or  ab- 
sent, and  the  Biceps  appears  as  arising  solel}'  from  the  glenoid 
margin. 

A  glance  at  the  arrangement  in  the  vertebrate  series  will  im- 
mediately indicate  that  the  origin  of  the  muscle  is  confined, 
strictly  speaking,  to  the  coracoid  element  of  the  pectoral  girdle. 
It  ma}^  arise  hy  a  single  head,  or,  as  in  man,  the  origin  may  be 
double,  hence  the  name. 

If,  as  in  us,  the  coracoid  is  reduced  and  the  scapula  corre- 
spondingly increased,  the  muscle,  if  it  preserves  its  double  origin, 
will  arise  b}-  one  head  from  the  small  coracoid  process,  by  the 
other  from  that  portion  of  the  glenoid  margin  which  is  con- 
tributed by  the  coracoid  bone.  If  the  long  tendon  of  the  glenoid 
head  of  our  Biceps  is  examined  in  subjects  between  the  ages  of 


1895.]  NEW    YOKE    ACADEMY    OP    SCIENCES.  235 

ten  and  puberty,  it  will  be  found  in  every  instance  connected 
with  the  so-called  sub-coracoid  centre  of  ossification. 

Hence  our  division  of  the  muscle  into  glenoid  or  scapular,  and 
coracoid  heads,  while  convenient  as  corresponding  to  adult  con- 
ditions, should  not  cause  the  fact  to  be  forgotten  that  the 
Biceps  is  entirely  a  coracoid  muscle  in  in  its  origin.  We  might, 
considering  the  probable  significance  of  our  coracoid  ossification, 
speak  of  the  coracoid  or  long  and  precoracoid  or  short  head  of 
the  muscle.  The  origin  of  the  Biceps  taking  place  in  this  man- 
ner from  a  single  skeletal  element,  it  is  not  surprising  to  find 
the  consolidation  of  the  two  heads,  which  are  present  in  man 
and  the  primates  generally,  to  be  of  very  frequent  occurrence  in 
lower  forms.  It  will  then  depend  upon  the  prominence  of  the 
coracoid  element,  and  the  relation  of  the  origin  to  the  glenoid 
socket,  whether  this  single  head  will  be  denominated  as  the 
coracoid  or  glenoid  muscle. 

B.  Insertion. 

In  like  manner  we  find  a  considerable  range  in  variation  in  the 
insertion  of  the  muscle.  It  may  be  attached  to  either  or  both 
bones  of  the  forearm,  according  to  the  functional  character  of 
the  limb,  and  the  specialization  of  rotatory  radial  movements  of 
the  forearm  and  hand.  Moreover,  in  forms  presenting  the  origin 
by  two  heads  from  the  pectoral  girdle,  either  or  both  of  the 
girdle  heads  may  be  connected  with  either,  or,  hy  division  of  the 
insertion,  with  both  of  the  forearm  bones. 

Consequently  the  analysis  of  the  Biceps  muscle  would  result 
as  follows,  retaining  the  names  "  glenoid  "  and  "  coracoid  "  as 
designating  respectively  the  outer  and  inner  girdle  origins  of 
the  muscle  : 

Complete  type  form  of  muscle,  four  heads. 

1.  Gleno-radial.  3.   Goraco-radial. 

2.  Gleno-ulnar.  4-    Coraco-ulnar. 

This  type  becomes  inodified  in  various  forms  by  reduction 
and  elimination  of  two  or  more  heads,  so  as  to  present  a  number 
of  variations.  Krause*  first  pointed  out  this  quadricipital 
character  of  the  human  Biceps,  based  on  careful  dissection  of 
the  muscle  and  analj^sis  of  the  fibres  at  the  insertion.  He  also 
collected  a  number  of  comparative  anatomical  facts  in  support  of 
this  view  of  the  compound  character  of  the  muscle.  A  by  no 
means  exhaustive  consideration  of  the  structure  of  the  Biceps  in 
the  lower  animals  reveals  the  existence  of  the  following  reduc- 

*  W.  Krause,  Specielle  und  Macroscopische  Anatomie,  Hanover,  1879,  p.  223. 


236  TRANSACTIONS   OF    THE  [maY,  13, 

tions  ami   combinations  of  the  four  type  lieads  of  origin  and 
their  insertion. 

I.   Gleno-radial  alone. 

A  typical  instance  is  pi-esented  by  Talpa  europea.  Geohe- 
gan  *  describes  the  muscle  in  this  animal  as  follows  :  The  Bi- 
ceps is  single-headed,  arising  just  above  the  glenoid  articular 
surface  by  a  long  tendon  which  passes  through  a  groove  in  the 
extreme  anterior  end  of  the  humerus ;  this  groove  is  at  first  a 
tunnel.  It  is  onl}-  after  it  has  passed  the  elbow  that  the  muscle 
becomes  fleshy.  Insertion  below  the  middle  of  the  radius. 
Welcker  f  corrects  this  statement  to  read  that  the  insertion  is 
above  the  middle  of  the  radius. 

Other  forms  presenting  the  Glenro-radial  muscle  are  :  Nj'Cti- 
pitheeus,  Stenops,  Horse,  Ruminants,  |  Lutra  vulgaris. § 

II.  Goraco-radial  alone. 

This  form  of  the  Biceps  muscle  is  presented  by  Orycteropus 
capensis,  Rhinoceros,  Frog,  Toad,  Lacerta,  ||  Phoca  vitulina.^ 

In  this  animal  the  muscle  arises  from  the  coracoid  process, 
is  inserted  into  the  radial  tuberosity,  and  is  combined  with  a 
short  head,  which  is  connected  with  the  Brachialis  anticus. 

III.  Gleno-ulnai-  alone. 

The  muscle  occurs  in  this  form  in  H^'rax  capensis  and  in  Ro- 
dents generally.** 

lY.   Coraeo-ulnar  alone. 

Humphry .fl  in  describing  the  muscular  s^-stem  of  Crypto- 
branchus  japonicus  gives  the  following  account  of  the  Coraco- 
brachialis  longus. 

"  This  is  the  largest  muscle  arising  from  the  coracoid.  It 
arises  from  the  hinder  edge  of  the  coracoid  and  divides  into  two 
portions.  Of  these  the  larger  and  inner  or  lower  division  is  in- 
serted into  the  ulnar  edge  of  the  humerus  for  a  quarter  of  an 
inch  above  the  internal  condj'le  ;  the  other  division,  being  nearly 

*Geohegan,  Myology  of  the  Fore-limb  of  Talpa  europea,  Proceedings  Dublin 
Biolog.  Assoc,  Vol.  I.,  1875,  p.  5. 

t  Welcker,  H.,  Archiv  f.  Anatomic  und  Entwicklungsgeschichte,  1878,  p.  23. 

X  Krause,  op.  cit.,  p.  22?i. 

'i  Lucae,  J.  C.  G.,  Die  Robbe  und  Otter  (Phoca  vitulina  und  Lutra  vulgaris)  in  ihrem 
Knochen  und  Muskelskelet,  Frankfurt  a/ j,_  1873,  p.  204. 

I  Krause,  op.  cit.,  p.  223. 

\  Lucae,  op.  cit.,  p.  199. 

**  Krause,  op.  cit.,  p.  223.    W.  Krause,  Anatomic  des  Kaninchens,  p.  107. 

tt  Op.  Cit.,  p.  33. 


1895.]  NEW   YORK   ACADEMY    OE    SCIENCES.  237 

as  large,  is  partl}^  inserted  into  the  side  of  the  long  tendon  of 
the  Biceps,  while  a  bundle  of  its  fibres  is  continvied  on  over  the 
elbow,  and  is  inserted  into  the  ulna  near  the  joint.  The  last  de- 
scribed division  must  represent  the  short  or  coracoid  origin  of 
the  Biceps  in  man.  There  is  no  trace  of  it  in  Menobranch, 
Axolotl  or  Newt.  The  muscle  in  them,  though  large,  is  confined 
to  the  humerus  in  its  insertion." 

The  Coraco-radialis  or  Biceps  arises  from  the  external  sur- 
face of  the  coracoid,  between  the  Epicoraco-brachial  (Pectoralis 
minor)  and  the  short  Coraco-brachial,  as  a  fan  shaped  muscle,  the 
fibres  of  which  pass  across  the  short  Coraco-brachial  and  soon 
converge  into  a  long  tendon,  which  runs  down  beneath  the  Pec- 
toral. Having  passed  the  Pectoral  it  receives  the  fibres  of  the 
long  Coraco-brachial,  passes  over  the  elbow  joint,  and  is  inserted 
into  the  palmar  surface  of  the  upper  end  of  the  radius  close  to 
the  joint.  It  is  supplied  by  the  nerve  which  perforates  the  scap- 
ula and  which  supplies  also  the  superficial  Coraco-brachial. 

Y.   Gleno-radial  and  Coraco-radial. 

Meckel  *  describes  the  double-headed  Biceps  of  Ornithorrhyn- 
chus  paradoxurus,  one  head  arising  from  the  anterior,  the  other 
from  the  posterior  coracoid,  the  muscle  passing  to  be  inserted 
into  the  radius. 

YI.   Gleno-radial  and  Gleno-idnar . 

Dog. 

Origin :  By  a  single  strong  tendon  from  the  edge  of  the  glen- 
oid fossa,  the  tendon  passing  through  the  capsular  ligament  of 
the  joint. 

Insertion:  By  a  strong  tendon  chiefly-  into  the  ulna,  although 
attached  also  to  the  radius  by  a  smaller  slip. 

Other  forms  presenting  the  same  arrangement  of  the  muscle  : 

Choloepus  didact^-lus.f 

Two-toed  sloth. 

Origin:  ^y  a  long  and  strong  tendon  from  the  glenoid  border  of . 
the  scapula,  passing  down  through  the  intertubercular  groove 
in  the  capsule  of  the  shoulder.  The  muscle  descends  on  the 
arm,  dividing  into  two  strongly  develoijed  bellies,  one  passing 
with  the  Pectoralis  and  Deltoid  to  the  tuberosity  of  the  radius, 
the  other  with  the  Brachialis  anticus  to  the  coracoid  process  of 
the  ulna. 

*  System  der  Vergleichenden  Anatomie,  p.  516. 

tLucae,  J.  C.  G.,  Der  Fuchsafie  und  das  Faulthier  (Lemur  macaco  and  Choloepus 
didactylus)  in  ihrem  Knochen-und  Muskelskelet,  Frankfurt  ^j  m,  1882. 


238  TRANSACTIONS    OF   THE  [MAY.  13, 

The  combination  of  glono-raxlial  and  gleno-uluar  muscle  is  also 
noted  in  the  Pig  and  Cat. 

YII.      Gleno-radial  and  Goraco-ulnar. 

Uromastix  spinipes.* 

Origin:  by  two  distinct  portions  from  coracoid,  one  tendin- 
ons  from  proximal  part,  the  other  muscular  more  laterally  from 
anterior  part,  corresponding  with  the  coracoid  and  glenoid 
origins  in  man. 

Insertion:  After  being  joined  by  Brachialis  anticus,  which 
is  large,  arising  from  the  lower  part  of  the  humerus,  the  con- 
joined tendon  is  inserted  into  the  radius  and  ulna. 

VIII.  Coraco-radial  and  Gleno-ulnar. 

In  Marsupials,  in  which  the  two  muscles  are  entirely  separate 
from  each  other.f 

IX.  Coraco-Radial  and  Coraco-Ulnar. 

This  arrangement  of  the  muscle  is  found  in  Em3'S  and  Cha- 
meleon.| 

A  general  consideration  of  the  facts  above  adduced  leads  to 
the  natural  conclusion  that  the  Biceps  muscle  of  the  fore-limb,  or 
its  homologue,  presents  throughout  the  vertebrate  series  evi- 
dences in  its  structure  and. arrangement  of  a  general  type-plan 
of  construction,  modified  in  the  ditferent  groups  by  the  functional 
requirements  of  the  Jimb,  and  in  all  probability'  b}'  the  varying 
relations  assumed  by  the  tendon  of  origin  to  the  capsule  and 
the  cavity  of  the  humero-scapular  articulation.  I  believe  that 
this  fundamental  type-construction  of  the  appendicular  muscular 
SA'stem  is  the  element  to  which  we  must  refer  for  the  explanation 
of  deviations  from  the  arrangement  normally  found  in  any-  one 
species.  Partial  returns  to  the  potential  t3'pe-form  constitute 
reversions  of  far  broader  significance  than  those  usually  grouped 
under  the  head  of  atavism. 

In  respect  to  the  human  subject,  as  well  as  in  the  case  of  the 
remaining  vertebrates,  and  especially  mammalia,  our  exact 
knowledge  regarding  the  lines  of  descent  of  present  orders  and 
sub-orders  is  still  so  rudimentary  and  imperfect,  that  the  im- 
propriet}'  of  referring  nearly  all  muscular  variations  to  atavism 
and  direct  inheritance  becomes  at  once  apparent.     The  fact  that 

♦Humphry,  op.  cit.,  p.  64. 
tKrause,  op.  cit.,  p.  223. 
JKrause,  op.  cit.,  p.  223. 


1895.]  NEW   YORK   ACADEMY   OF   SCIENCES.  239 

in  ease  of  any  given  human  muscular  variation,  a  muscle  of 
similar  character  is  found  in  one  of  the  lower  vertebrates  does 
not  warrant  the  assumption  that  both  are  derived  by  inheritance 
from  an  immediately  precedent  common  ancestral  form.  The 
form  in  which  the  variant  human  muscle  appears  normally  may 
be  incalculably  far  removed  from  man,  may  even  belong  to  a  dif- 
ferent vertebrate  class.  That  the  structural  coincidence  of  the 
two  muscles  is  to  be  taken  as  indicating  anything  more  than  the 
most  generalized  relationship  of  vertebrates  is  difficult  to  be- 
lieve. For  many  of  the  aberrant  muscular  conditions  observed 
in  man  a  very  comprehensive  view  as  to  their  derivation  must  be 
a,dopted.  I  believe  that  we  are  right  in  referring  such  varia- 
tions, as  will  be  considered  in  detail  below,  to  the  development 
of  an  inherent  constructive  type,  abnormal  for  the  species  in  ques- 
tion, but  revealing  its  morphological  significance  and  value  by 
appeai'ing  as  the  normal  condition  in  other  vertebrates. 

The  question,  as  far  as  it  affects  the  variations  to  be  considered, 
may  be  represented  graphically  somewhat  in  the  following  man- 
ner: 


X  y  X  y 

Fig.  1.  Type  form  of  Muscle.  FiG.  2.  Cleavage  variation. 

In  Fig.  1  let  the  line  a-b  represent  the  skeletal  origin,  the 
line  x-y  the  corresponding  insertion  of  a  muscular  plane. 
Oonsidering  this  arrangement  as  the  type,  in  which  the  entire 
space  between  origin  and  insertion  is  occupied  by  an  uninter- 
rupted muscular  plane,  it  will  become  apparent  that  modifica- 
tions of  this  type  can  take  place  in  two  ways, 

1.  Cleavage  variations,  retaining  in  general  the  original  scope 
of  origin  and  insertion,  in  which  the  original  muscular  plane  ap- 
pears as  two  or  more  distinct  muscles.     (Fig.  2.) 

2.  Reduction  variations,  where  a  portion  of  the  origin  or  of 


240 


TRANSACTIONS   OF   THE 

h 


[may  13, 


Fig.  3.  Keductioii  vari.ition;  Origin 
retained;  Insertion  reduced. 


Fig.  4.   Eeduction  variation;  Origin 
retained ;  Insertion  reduced. 


Fig.  5.  Reduction  variation;  Oiigin 
and  Insertion  reduced;  Points  re- 
tained. 


Fig.  6.  Reduction  variation;  Origin 
and  Insertion  reduced;  Points  ex- 
changed. 

h 


Fig.  7.  Reduction  variation;  Origin 
and  Insertion  rediiced;  Points  re- 
tained. 


Fig.  8.  Reduction  variation;  Origin 
and  Insertion  reduced ;  Points  ex- 
changed. 


1895.]  NEW   YORK   ACADEMY    OF   SCIENCES 

h 


241 


Fig.  9.  Eeduction  variation;  Origin 
reduced. ;  Insertion  retained. 


Fig.  10.  Eeduction  variation;  Origin 
reduced;  Insertion  reta,ined. 


the  insertion,  or  of  both,  is  eliminated,  necessitating,  under 
some  conditions,  a  change  in  the  direction  of  the  muscular  fibres. 

These  variations  are  represented  schematically  by  Figs.  3-10, 
it  being  of  course  evident  that  the  arbitrarily  selected  points  a 
and  &,  and  x  and  y.  may  be  placed  anywhere  along  the  lines  of 
origin  and  insertion  respectively. 

In  defining  the  following  variations  in  the  human  Biceps  I  pre- 
fer to  accentuate  this  relation  to  a  fundamental  vertebrate  type- 
plan,  and,  at  the  expense  of  introducing  an  additional  term  into 
the  complex  reversional  nomenclature,  I  will  speak  of  them  as 
"  Myo-typical  Reversions.'''' 

In  man  the  Biceps  is  composed  of  the  Gleno-radial  and  Coraco- 
radial  divisions,  combined  with  a  superficial  ulnar  fasciculus, 
possessing  a  fascial  insertion  along  the  ulnar  border  of  the  fore- 
arm by  means  of  the  semilunar  fascia. 

We  may  group  the  variations  which  concern  us  here  with 
reference  to  the  derivation  and  destination  of  the  accessory 
portions,  representing  additional  glenoid  and  coracoid  heads, 
which  have  lost  their  distal  ulnar  attachment. 

I.  Gleno-ulnar  Head. 
Appears  in  the  following  forms  : 

1.  Capsulo-pectoeal  tendon. 
Diagnosis  :  Tendinous  fibres  in  the  form  of  scattered  bundles, 
or  more  compactly  arranged  as  distinct  tendon-bands,  arising  in 
conjunction  with  the  capsular  ligament  from  the  glenoid  margin  of 
the  scapula,  differentiating  from  the  capsule  at  the  upper  border  of 
the  intertubercular  groove  and  extending  downwards  over  the 

Transactions  N.  Y.  Acad.  Sci.,  Vol.  XIV.,  Sig.  16,  August  28, 1895. 


242  TRANSACTIONS   OF   THE  [mAY  13, 

long  gleno-radial  head,  rooting  in  the  bicipital  canal  and  merg- 
ing with  the  deep  surface  of  the  tendon  of  the  Pectoralis  major, 
or,  in  some  instances,  extending  beyond  the  pectoral  tendon  to 
the  deep  fascia  of  the  arm. 

This  is  the  most  common  form  in  which  the  variation  presents 
itself. 

Cases  : 

1.  9,  white,  U.  S.,  aet.  62.     January  30,  1894. 
Plate  XVII.     Right  upper  extremity: 

A  distinct  tendon,  imbedded  in  the  capsule  of  the  joint,  over- 
h'ing  the  intertubercular  groove,  covering  the  long  bicipital 
tendon  and  passing  to  the  deep  surftice  of  the  Pectoralis  major 
tendon,  on  which  it  spreads  out  in  the  upper  third,  terminating 
b}-  interlacing  with  the  pectoral  tendon  fibres. 

Left  upper  extremity  : 

Presents  the  same  slip,  more  strongly  developed,  extending 
nearly  to  the  lower  border  of  the  Pectoralis  major  tendon. 

Plate  XVIII.  Capsule  between  the  tuberosities  partly  divided, 
to  show  the  deep  position  of  the  tendon  imbedded  in  the  shoulder 
capsule,  and  indicating  a  tendenc}'  toward  intra-articular  immi- 
gration. 

Plate  XIX.  The  same  joint  opened  from  behind,  with  head  of 
humerus  removed.  The  thickened  strand  on  the  inner  surface  of 
the  anterior  wall  of  the  capsule,  just  in'front  of  the  long  Biceps 
tendon,  is  directlv  continuous  with  the  fibres  of  the  tendon  slip. 

2.  S \  Austria, \aet.  05.     October  11,  1893. 
Plate  XX.     Right  upper  extremity. 

Strong  fibrous  band  arising  from  capsule  over  lesser  tuber- 
osity, and  descending  over  long  tendon  of  Biceps,  connected 
with  deep  surface  of 'Pectoralis  major  tendon,  to  the  lower  mar- 
gin of  which  it  extends. 

A  tendon  band  from  anterior  part  of  capsule  passes  to  outer  mar- 
_gin  of  short  head,  indicating  tendency  to  subdivision  of  this  head. 

3.  9.  Germany,  aet.  84. ''  November  9,  1893. 
■Plate  XXI.     Right  upper  extremity. 

Well  marked  strong  fibrous  fasciculus,  extending  from  cap- 
sule of  shoulder  joint  over  the  bicipital  groove  and  contents  to 
the  deep  surface  of  the  Pectoralis  major  tendon.  Some  fibres 
merge  with  the  pectoral  tendon,  while  others  continue  below  its 
inferior  margin  to  join  the  deep  fascia  of  the  arm. 

The  left  upper  extremity  of  the  same  subject  presents  a 
transition  to  the  form  next  to  be  described  (Gleno-uluar  muscle). 
A  strong  tendinous  band,  incorporated  at  its  origin  in  the  cap- 
sule of  the  shoulder  joint,  passes  downward,  covering  in  the  bi- 
cipital groove  and  attaching  itself  to  the  upper  margin  and  deep 


1895.]  NEW   YORK   ACADEMY    OF    SCIENCES.  243 

surface  of  the  Pectoralis  major  tendon.  In  part  continuous 
with  this  tendon  band,  in  part  arising  independently  from  the 
deep  surface  of  Pectoralis  tendon,  four  muscular  slips  arise,  the 
two  upper  passing  backward,  the  two  lower  downward,  to  in- 
corporate themselves  with  the  substance  of  the  Biceps  muscle. 
The  bundles  are  all  distinctly  muscular  in  character. 

The  following  additional  instances,  in  which  the  aboA'e  de- 
scribed band  was  present,  were  noted  in  the  series : 

4.  ^,  U.  S.  white,  aet.  38.     December  27,  1893. 

Small  glenoid  tendon  slip  joining  deep  surface  of  Pectoralis 
major  tendon  over  the  bicipital  groove.     Present  on  both  sides. 

5.  9  Ireland,  aet.  72.     January  9,  1894. 
Slip  present  on  both  sides. 

6.  $  Ireland,  aet.  40.     December  21,  1893. 
Right  upper  extremity. 

Large  tendon  band,  arising  from  capsule  external  to  long 
head  of  Biceps,  inserted  on  deep  surface  of  Pectoralis  major 
tendon. 

7.  $  Ireland,  aet.  32.     November  28,  1893. 
Right  side. 

8.  S  Germany,  aet.  54. 

Large  band  on  left  side.  Insertion  confined  to  Pectoralis 
major  tendon. 

9.  $  Germany,  aet.  52.     December  14,  1893. 
Right  side. 

Very  large  tendon  \  inch  wide,  passing  from  glenoid  margin 
interwoven  with  the  capsule,  to  the  united  bellies  of  Biceps,  with 
intermediate  attachment  to  the  deep  surface  of  Pectoralis  major 
tendon. 

10.  $  Ireland,  aet.  40. 
Both  extremities. 

Strong  tendon  from  glenoid  edge  to  deep  surface  of  Pectoralis 
major  tendon. 

11.  $  Italy,  aet.  50. 
Right  side. 

Very  broad  tendon  slip,  in  part  continued  beyond  Pectoralis 
tendon  into  the  Biceps. 

12.  9  ,,IJ.  S.,  negro,  aet.  24. 
Left  side : 

Glenoid  tendon  to  junction  of  heads  of  Biceps. 

2.     Gleno-Dlnar  Muscle. 

Occurs  in  three  forms  or  variations  : 

(a.)  Origin  identical  loith  that  of  the  Capsulo-pectoral  tendon, 
passing  downward  and  presenting  a  more  or  less  close  connection 


244  TRANSACTIONS    (»F    THE  [MAV  13, 

xcith  the  deep  surface  of  the  Pectoralis  major  tendon.  Becoming 
muscular  a  short  distance  beyond  the  loiver  border  of  the  Pec- 
toralis tendon  the  slip  passes  obliquely  inivards  across  the  long 
head,  fusing  with  its  anterior  surface  and  inner  margin,  or 
joining  the  outer  margin  of  the  shoi't  coracoid  head. 

Cfl.SGS  '. 

1.  i,  U.  S.,  white,  aet.  24.     November  29, 1893. 
Plate  XXII.     Right  side. 

A  strong  shining  tendinous  band  arises  from  the  glenoid 
margin  incorporated  with  the  shoulder  capsule.  Passing  down 
and  emerging  from  beneath  the  edge  of  the  coraco-acromial 
ligament,  the  tendon  becomes  closely  connected  with  the  deep 
surface  of  the  Pectoralis  major  tendon,  interlacing  with  its  fibres 
at  right  angles,  iN'ing  upon  the  long  tendon  of  the  Biceps  and 
forming  the  main  portion  of  the  roof  of  the  inter-tubercular 
groove.  Toward  the  lower  portion  of  the  pectoral  tendon  the 
inner  half  of  the  slip  gradually  separates  itself  from  the  same 
and  forms  a  small  muscular  belly  which  joins  the  outer  margin 
of  the  short  biciptal  head  near  its  junction  with  the  long  head. 
The  outer  portion  of  the  tendon  slip  gradually  passes  deeper 
into  the  substance  of  the  Pectoralis  tendon,  with  which  it  is  in- 
tricately interlaced.  On  the  bottom  of  the  inter-tubercular 
groove  are  several  well  marked  longitudional  tendinous  bands, 
connected  below  with  the  tendon  of  the  Pectoralis  major  ;  above 
they  in  part  separate  from  the  tendon,  passing  upward  and  in- 
ward and  crossing  at  right  angles  the  tendon  fibres  of  Latissimus 
dorsi  and  Teres  major;  in  part  they  go  upward  and  outward,  1\'- 
iug  in  the  floor  of  the  bicipital  groove  under  cover  of  the  long 
Biceps  tendon. 

A  small  third  internal  humeral  head  of  the  Biceps  is  present 
in  the  same  arm,  derived  from  the  Coraco-brachialis  insertion. 

2.  ^  ,  U.  S..  white,  aet.  50. 

Plate  XXIII.     Right  upper  extremit}-. 

Tendon  slip  with  intermediate  attachment  to  deep  surface  of 
Pectoralis  major  tendon,  arising  in  connection  with  capsular 
ligament  from  the  glenoid  margin,  and  passing  to  the  inner  bor- 
der of  the  long  bicipital  head,  at  the  line  of  junction  with  the 
short  head. 

3.  .?,  Ireland,  aet.  32.     November  29,  1893. 

Plate  XXTIII.  Left  upper  extremity  of  subject,  whose  right 
upper  extremity-  presents  the  variation  described  under  "  b  2," 
Plate  XXYII.  vidi  ibid. 

4.  $  ,  U.  S.,  negro,  aet.  50.     December  14,  1893. 
Plate  XXIY.     Right  side. 

Tendon  in  part  fused  with  deep  surface  of  Pectoralis  major 


1895.]  NEW    YORK   ACADEMY   OF   SCIENCES.  245 

tendon  at  the  lower  border  of  which  a  short  muscular  belly  de- 
velops which  joins  the  Biceps. 

Between  the  long  and  short  bicipital  heads  an  additional  ten- 
don slip  arises  from  the  capsule,  near  the  base  of  the  coracoid 
process,  and,  passing  down  on  the  outer  side  of  the  short  Biceps 
tendon,  receives  some  upper  fibres  of  insertion  of  a  short  Coraco- 
brachialis  superior,  and  then  joins  the  outer  margin  of  the  short 
Biceps  head  just  before  the  latter  meets  the  long  head. 

The  left  side  of  the  same  subject  presents  an  instance  of  the 
next  succeeding  form. 

5.  <?  ,  Germany,  aet.  52.     December  14,  1893. 

Yery  large  accessory  glenoid  head,  ^"  broad,  passing  to  the 
united  bellies  of  the  Biceps.  Upper  tendinous  portion  very 
distinct  and  adherent  to  Pectoralis  tendon. 

6.  $,  TJ.  S.  white,  aet.  23.     January  30,  1894. 
Plate  XXY.     Left  upper. 

Gleno-ulnar  tendon  connected  but  loosely  with  deep  surface 
of  Pectoralis  major;  leaves  tendon  of  Pectoral  as  a  distinct 
band  at  about  the  middle  of  its  posterior  surface  and  a  short 
distance  below  the  distal  margin  of  the  pectoral  tendon,  ex- 
pands into  a  superficial  broad  and  flat  muscular  belly,  which 
descends  upon  the  long  bicipital  head,  lying  in  close  connection 
with  the  outer  margin  of  the  coracoid  head  from  which  it  is 
completely  separable  to  a  point  midway  between  the  lower 
border  of  the  Teres  major  and  Latissimus  dorsi  and  the  elbow. 
The  fibres  of  this  accessory  head  then  join  the  coracoid  head 
along  its  external  border.  About  3  cm.  above  the  internal 
condyle  the  long  head  joins  the  tendon  of  insertion,  developed 
on  the  deep  and  external  aspect  of  the  combined  coracoid  and 
accessor}^  heads. 

The  bicipital  fascia  receives  some  superficial  and  oblique 
fibres  (decussating)  from  the  outer  and  anterior  aspect  of  the 
radial  tendon. 

The  right  arm  of  the  same  subject  presents  a  Gleno-epitroch- 
lear  slip  {vide  infra). 

(6.)  Tendon  of  origin  of  Gleno-ulnar  muscle  is  comi:)letely 
free  from  Pectoralis  major  tendon,  under  cover  of  which  it  lies. 

Cases  :  - 

1.   ^,  r.  S.,  negro,  aet.  50.     December  14, 1893. 

Plate  XXVI.  Left  upper  extremity  of  subject  whose  right 
extremity  is  described  under  "  a  4,"  Plate  XXIV. 

Long,  distinct  glenoid  tendon,  overlying  long  bicipital  ten- 
don, under  cover  of  Pectoralis  major,  but  not  connected  with 
the  same.  Becomes  muscular  opposite  lower  third  of  pectoral 
tendon  and  crosses  over  long  bicipital  head  to  join  its  inner 
margin  at  about  the  middle  of  the  arm. 


246  TRANSACTIONS   OF   THE  [mAY  13, 

2.    <?,  Ireland,  aet.  32.     November  29,  1893. 

Plate  XXYII.  Rii^ht  upper  extremity.  Under  cover  of  in- 
sertion of  Peetoi-nlis  major,  a  broad  tendinous  band  descends 
over  the  intertubercular  groove,  derived  from  the  shoulder  cap- 
sule and  covering  the  long  tendon  of  the  Biceps,  to  which  it  is 
connected  by  a  thin  but  strong  tendinous  lamina.  The  lower 
portion  of  this  band  terminates  in  a  broad  muscular  sheet,  which 
turns  inwards  to  join  the  medial  margin  of  the  long  head. 

A  few  scattered- tendinous  fibres  descend  oblifpiely  from  the 
capsule  to  the  outer  margin  and  anterior  surftxce  of  the  lesser 
head. 

The  left  upper  extremity  of  the  same  subject  presents  the 
gleno-ulnar  slip  with  intermediate  connection  to  the  deep  pec- 
toral tendon.     (Variety  "a.")     Plate  XXYIII. 

Here  a  strong  tendinous  band,  arising  from  the  intertubucular 
portion  of  the  capsule,  and  connected  with  the  upper  part  of  the^ 
deep  surfiice  of  the  Pectoralis  tendon,  becoming  free  below,' 
crosses  obliquel_v  over  the  long  bicipital  tendon  to  fuse  with  the 
inner  margin  of  its  muscular  belly  a  short  distance  before  the 
same  is  joined  by  the  coracoid  head. 

A  small  tendinous  bundle  (Capsulo-intermediate  fibres),  aris- 
ing from  the  coracoid  portion  of  the  capsule,  accedes  to  the  outer 
pare  of  the  coracoid  head. 

Insertion  of  Biceps  in  this  arm:  Radial  tendon  derived  as 
usual  from  the  deep  surface  of  the  combined  muscle.  Superfi- 
ciall}-  some  fibres  pass  from  the  outer  part  of  the  muscle  across 
the  radial  tendon  into  the  semilunar  fascia,  which  is  inserted  by 
a  forked  process  into  the  radial  as  well  as  the  ulnar  side  of  the 
deep  forearm  fascia. 

c.    Transition  forms  between  "a"  and  "6,"  and  variations. 

Cases  : 

1.  S  ,  Ireland,  aet.  53.     March  16,  1894. 
Plate  XXIX.     Left  upper  extremity. 

Gleno-ulnar  tendon  slip,  presenting  a  reduplication  of  the 
origin.  The  outer  band  is  connected  with  the  Pectoralis  major 
tendon  ;  the  inner  is  free.  They  join  opposite  the  middle  of  the 
pectoral  tendon  and  develop  a  ?tout,  muscular  bell}',  which  can 
be  followed  as  far  as  the  elbow,  where  a  few  of  the  deeper  fibres 
pass  into  the  inner  margin  of  the  radial  tendon  of  insertion, 
whereas  the  remainder  of  the  xleep  and  all  the  superficial  fibres 
of  the  accessory  head,  joined  b}-  some  from  the  outer  margin  of 
the  main  muscle,  pass  inward  into  the  bicipital  fascia. 

2.  S,  Ireland,  aet.  35.     March  14,  1894. 
Plate  XXX.     Left  upper  extremity. 

Gleno-ulnar  tendon,  double  at  origin,  a  portion  passing  into 


1895.]  NEW   YORK   ACADEMY   OF   SCIENCES.  247 

the  pectoral  tendon,  the  remainder  into  the  outer  margin  of  the 
short  bicipital  head  and  into  the  Coraco-brachialis,  which  muscle 
is  strongly  developed  in  its  upper  part. 

3.   $,  German}--,  aet.  64.     October  14,  1893. 

Plate  XXXI.     Right  upper  extremity. 

Double  glenoid  tendon,  the  outer  division  giving  otT  a  branch 
to  join  the  deep  surface  of  the  pectoral  tendon.  The  tendons  of 
origin  then  unite  and  form  a  muscular  belly  which  passes  down 
and  in  over  the  long  bicipital  head  to  join  the  deep  surface  and 
outer  margin  of  the  short  head. 

3.  Gleno-epitrochlear  Tendon. 

Diagnosis:  Origin  as  Capsulo-pectoral  fibres  from  glenoid 
margin  with  capsule  of  shoulder.  Connected  with  deep  surface 
of  Pectoralis  major  tendon  at  the  lower  border  of  which  the 
fibi'es  are  gathered  into  a  long,  slender  tendon  which  passes 
obliquely  down  and  in,  across  the  Biceps,  brachial  vessels  and 
large  nerves,  to  be  inserted  into  the  anterior  part  of  the  internal 
epicondyle. 

The  structure  exhibited  by  this  variation  in  its  upper  portion 
is  such  as  to  admit  of  no  doubt  of  its  identity  with  the  fibres 
described  above  as  Capsulo-pectoral  and  Gleno-ulnar  with  inter- 
mediate pectoral  connection. 

The  lower  long  tendon  with  its  epicondylar  implantation  rep- 
resents, I  believe,  a  rudimentary  Gleno-ulnar  muscle,  whose  in- 
sertion has  been  shifted  to  the  internal  epicondyle.  The  latter 
is  a  point  frequently  selected  for  the  insertion  of  aberrant  and 
rudimentary  tendon  slips,  as  instanced  by  the  Dorso-epitroch- 
learis  and  Chondro-epitrochlearis  muscles. 

The  supposition  that  the  variation  just  mentioned  and  some 
of  the  previousl}^  described  bicipital  variations  can  be  brought, 
into  connection  with  aberrant  pectoral  muscle  or  tendon  slips 
is  refuted  by  the  constant  connection  with  the  capsule,  and  by 
means  of  the  same  with  the  glenoid  margin  of  the  scapula. 

The  pectoral  varieties  described  as  Chondro-humeral,  Chondro- 
coracoid  and  Chondro-epitrochlear  muscles  are  connected,  at 
times  with  the  lower  border  of  the  pectoral  muscle  and  tendon, 
but  they  are  evidently  derivatives  from  the  pectoral  plane,  and 
never  assume  the  characteristic  relation  to  the  deep  surface  of 
the  pectoral  tendon  and  shoulder  capsule  exhibited  by  the  bi- 
cipital variations  above  described. 

I  have  met  with  four  well-marked  instances  of  the  Gleno- 
epitrochlear  tendon  in  the  series  examined. 

Cases  : 


248  TRANSACTIONS   OF    THE  [MAY  13, 

1.  <?,  Germany,  net.  66.     January  11,  1894. 
Plate  XXXII.     Left  upper  extremity- 

Glenoid  tendon,  overlying  long  Biceps  tendon  and  fusing  with 
the  under  surface  of  the  Pectoralis  major  tendon  in  its  broad 
upper  part.  About  the  middle  of  the  pectoral  tendon  this 
connection  ceases,  and  the  tendon  bundle  becomes  narrower  and 
more  sharply  defined.  It  remains  tendinous  throughout  and 
passes  obliquel}'  downward  and  inward  over  the  Biceps,  median 
nerve  and  brachial  artery  to  be  attached  to  the  anterior  aspect 
of  the  internal  epicondyle. 

In  confirmation  of  the  view  expressed  as  to  the  nature  of  this 
variation  the  right  upper  extremit}'  of  the  same  subject  pre- 
sented the  Capsulo-pectoral  slip,  as  a  well-marked  tendon,  con- 
nected with  the  deep  surface  of  the  Pectoralis  major;  also  a 
separate  slender  tendon  from  the  coraco-acromial  ligament  to 
the  outer  margin  of  the  short  bicipital  head. 

2.  ,?,  Ireland,   aet.  42.     November  13,  1894. 
Plate  XXXIII.     Left  upper  extremity. 

A  tendon  from  the  glenoid  margin,  interwoven  with  the  cap- 
sule of  the  shoulder  joint,  passes  over  the  long  Biceps  tendon, 
covered  by  the  Pectoralis  major  tendon,  to  the  deep  surface  of 
which  it  is  partially  attached,  and  continues  bevond  the  pectoral 
tendon  as  a  slender  but  very  distinct  band,  passing  obliquely 
downward  and  inward  over  the  brachial  artery  and  the  large 
nerves  to  the  internal  epicondyle,  blending  with  the  lower  quarter 
of  Struther's  ligament. 

3.  (?,  Germany,  aet.  66.     January  11,  1894. 

Left  upper  extremity  presents  exactly  the  same  arrangement. 

4.  ,?,  U.  S.,  white,  aet.  23.     January'30,  1894. 
Right  upper  extremity. 

Gleno-ulnar  fibres,  rather  weak  in  upper  portion,  on  posterior 
surface  of  Pectoralis  major  tendon. 

From  the  lower  part  of  the  posterior  surface  of  pectoral 
tendon,  and  from  inferior  border  of  deep  reflected  part,  fibres 
are  derived  which  form  a  slender  tendon,  passing  down  and  in, 
superficial  to  and  obliquely  across  Biceps  and  brachial  vessels 
:and  nerves,  to  be  inserted  on  the  anterior  surface  of  the  internal 
.epicondyle. 

4.  M.  Brachio-ulanris  lateralis. 

I  have  placed  under  this  designation  certain  of  the  variations 
of  the  Biceps,  constituting  accessory  third  humeral  heads,  aris- 
ing from  the  anterior  or  external  surface  of  the  shaft,  because  a 
careful  examination  atlords  grounds  for  regarding  them  as  dis- 
tal portions  of  a  Gleno-ulnar  muscle,  which  has  lost  its  proximal 


1895.]  NEW    YORK    ACADEMY    OF    SCIENCES.  249 

or  origin  portion,  represented  by  the  variations  just  described, 
and  has  obtained  a  secondary  attachment  to  the  humerus  near 
the  bicipital  groove  and  the  insertion  of  the  Pectoralis  major. 

This  group  would  therefore  form  the  last  of  a  series  of  varia- 
tions  of  a  muscle  arising  from  the  glenoid  margin  and  finding 
its  insertion  at  the  ulnar  border  of  the  forearm. 

Cases  : 

1.  9,  Ireland,  aet.  21.     October  25,  1893. 

Plate  XXXIY.  Both  upper  extremities  present  the  same 
Tariation. 

A  third  additional  Biceps  head  arises  from  the  outer  surface 
of  the  humeral  shaft  and  capsule  of  the  shoulder  joint,  and  from 
s,  strong  tendinous  band  into  which  the  upper  fibres  of  a  Coraco- 
brachialis  brevis  are  inserted. 

The  connections  with  the  shoulder  capsule,  found  in  the  Cap- 
s-ulo-pectoral,  Gleno-ulnar  and  Gleno-epitrochlear  variations,  is 
retained  in  this  instance  as  one  of  the  points  of  origin  of  the 
accesssory  head. 

2.  9,  It.  S.  negro,  aet.  24.     December  2t,  1893. 
Plate  XXXY.     Right  upper  extremity. 

A  third  bicipital  head  arises  from  the  anterior  surface  of  the 
shaft  of  the  humerus,  almost  directly  continuous  with  the  lower 
margin  of  the  Pectoralis  major  tendon  and  attached  to  the  lower 
portion  of  the  bicipital  groove. 

The  muscle  passes  down  on  the  outer  side  of  the  arm,  sepa- 
rated from  the  upper  and  outer  portion  of  the  Brachialis  anticns 
by  some  branches  of  the  musculo-cutaneous  nerve  and  muscular 
arterial  branches.  It  then  turns  inwards  beneath  the  main 
muscle  to  join  the  common  tendon  on  the  deep  aspect  and  along 
the  ulnar  margin. 

5.  Combination  of  Capsulo-pectoral  or  Gleno-ulnar  with 

Gleno-epitrochlear  fibres. 
Case: 

$,  U.  S.,  white,  aet  23.     January  80,  1894. 
The  two  extremities  present  the  variations  already  described 
as  follows: 

Right  upper.     Gleno-epitrochlear  tendon  (No.  4). 

Left  upper.     Gleno-ulnar  muscle,  "  a,"  No.  6,  Plate  XXY. 

6.  Combination    of  Tendinous  Gleno-ulnar  and  Coraco-Epi- 

trochlear. 
Case: 

9,  Ireland,  aet.  72.     January  9,  1894. 
Plate  XXXYI.  Right  upper  extremity. 


250  TRANSACTIONS   OF    THE  [MAY  13, 

A  slightly  markt'd  tenclinous  gleno-ulnav  slip  passes  from  the 
capsule  of  the  *^houldel•  over  the  intertubercular  groove,  with 
intermediate  attachment  to  deep  surface  of  pectoral  tendon,  to 
the  angle  of  union  between  the  long  and  short  bicipital  heads. 

Fiom  the  anterior  surface  of  the  lower  part  of  the  Coraco- 
brachialis,  near  its  insertion,  is  derived  a  slender  muscle-sMp, 
which,  becoming  tendinous,  passes  obliquely  down  and  in  over 
brachial  vessels  and  median  nerve  to  be  attached  to  the  internal 
epicondyle. 

The  left  upper  extremity'  of  the  same  subject  presents  a  small 
tendinous  band  passing  from  the  capsule  to  the  deep  surface  of 
the  Pectoralis  major  tendon. 

II.  Coraco-Ulnar  Head. 

This  muscle  is  found  usually  very  closely  fused  in  its  proxi- 
mal part  with  the  short  or  corao-radial  head  of  the  Biceps,  and 
with  the  Coraco  brachialis.  But  its  distal  portion  appears  fre- 
quently as  the  "  third  internal  humeral  head.''"' 

The  following  variations  are  to  be  noted  : 

1.  Capsula-intermediate  Tendon. 

Oriijin:  Tendon  fibres  derived  from  the  capsule  of  the 
shoulder  joint  between  the  coracoid  process  and  bicipital  groove. 
The  slip  passes  down  to  the  angle  of  fusion  between  the  long 
and  short  heads  of  the  Biceps. 

Cases : 

In  combination  with  capsulo-pectoral  fibres  in  the  following 
previously  described  instances  : 

1.  ^  ,  IJ.  S.,  negro,  aet.  -SO.     December  14,  1893. 
"2%"No.  4.     Plate  XXIV.     Well  marked  on  right  side. 

2.  S  ,  Ireland,  act.  32.     iNovember  29,  1893. 

"2^"  No.  2.  Plate  XXVII.  Especially  well  marked  on  left  side. 

3.  $  ,  Germany,  aet.  66.     January  11,  1894. 
Right  upper  extremity.     ''  3  "  No.  1. 
Additional  cases. 

4.  9,  Italy,  aet.  3U.     October  31,  1893. 
Both  upper  extremities. 

A  strong  fibro-tendinous  band  arising  from  the  inner  part  of 
the  capsule  of  the  shoulder  passes  vertically  down  to  be  attached 
to  the  septum  between  the  long  and  short  Biceps  heads. 

5.  ^,  U.  S.,  white,  aet.  27.     December  31,  1893. 
Right  upper  extremit}'. 

Slender  tendon  from  inner  part  of  shoulder  capsule  to  outer 
margin  of  lesser  bicipital  head. 


1895.]  NEW   YORK   ACADEMY   OP   SCIENCES.  251 

Macalister  *  describes  several  varieties  of  additional  coracoid 
heads  of  the  Biceps  (catalogue  numbers  11-14  incL).  The  ac- 
cessory portion  maj^  join  the  main  body  of  the  muscle,  or  else  it 
may  unite  with  the  normal  coracoid  head,  before  that  portion  of 
the  Biceps  joins  the  long  head.  Additional  coracoid  origins 
from  the  Coraco-acromial  ligament  and  from  the  insertion  tendon 
of  the  Pectoralis  minor  are  also  mentioned  by  the  same  author. 

2.    CoRACO-EPITROCHLARIS. 

As  in  the  case  of  the  Gleno-ulnar  head  certain  instances  occur 
in  which  an  additional  coracoid  head  passes  to  the  internal  epi- 
condyle.     I  have  met  this  arrangement  in  two  forms  : 

a.    Goraco-eintrochlear  tendon. 

Cases  : 

1.  ^ ,  U.  S.  white,  aet.  47.     March,  1894. 
Plate  XXXYII.     Right  upper  extremity. 

A  slender,  firm  tendon  arises  from  the  coracoid  process  at  the 
inner  border  of  the  short  bicipital  head  and  superficial  to  the 
Coraco-brachialis  origin.  It  passes  downward  and  slightly  in- 
ward obliquely  over  the  brachial  artery  and  the  large  nerves, 
receives  near  the  elbow  an  accession  of  fibres  from  the  internal 
intermuscular  septum,  and  is  inserted  into  the  internal  epicon- 
dyle. 

2.  ^  ,  Ireland,  aet.  63.     November  14,  1894. 
Right  upper  extremity : 

A  thin  tendinous  slip  arises  from  the  intermuscular  septum 
betwteen  the  short  head  of  the  Biceps  and  the  Coraco-brachialis, 
passes  downward  and  inward,  over  the  musculo-cutaneous  nerve 
to  the  internal  epicondj^le. 

The  musculo-cutaneous  nerve  passes  entirely  below  the  Cor- 
aco-brachialis, between  this  muscle  and  the  short  bicipital  head, 
the  former  receiving  its  nerve  higher  up  by  a  separate  branch 
from  the  outer  cord  of  the  brachial  plexus. 

3.  ^,  TJ.  S.  white,  aet.  34.     February  1,  1894. 
Left  upper  extremity  : 

A  tendon  slip  arises  from  the  coracoid  process  and  tendon  of 
origin  of  the  Coraco-brachialis  and  short  bicipital  head  ;  becom- 
ing free  about  2  cm.  below  the  coracoid  it  passes  downward  and 
inward  as  a  distinct  tendon  to  be  inserted  into  the  internal 
epicondjde. 

4.  ^ ,  TJ.  S.  white,  aet.  39.     December  14,  1893. 
Left  upper  extremity  : 

A  tendon  slip  from  origin  of  Coraco-brachialis  and  short  head 

*  Op.  cit.,  p.  80. 


252  TRANSACTIONS   OF   THE  [MAY  13, 

of  Biceps  crosses  over  the  brachial  vessels  and  the  nerves  to 
the  internal  epicondyle. 

The  long  tendon  of  the  Biceps  in  this  arm  is  doubled. 

5.  ?,  Ireland,  aet.  72.     January  9th,  1894. 

Combined  with  tendinous  Gleno-ulnar  band  in  right  arm  (vide 
I.  6,  Plate  XXXVI). 

b.  Coraco-epitrochlear  and  Gleno-epitrochlear  tendon  combined. 
Case  : 

S,  U.  S.,  white,  aet.  46.     November  11,  1893. 

Plate  XXXVIII.     Right  upper  extremity. 

A  coraco-epitrochlear  tendon,  arising  from  Coracoid  process 
at  point  of  junction  between  Coraco-brachialis  and  short  bicipital 
head,  passes  down  as  above  described  over  the  brachial  vessels 
and  the  large  nerves,  and  is  joined  at  about  the  middle  of  the 
arm  l^v  a  second  similar  tendon  which  arises  from  the  outer  por- 
tion of  the  capsule  of  the  joint,  descends  beneath  Pectoralis 
major  tendon  and  then  crosses  obliquely  down  and  in  over  the 
short  bicipital  muscle.  The  conjoined  tendons  continue  down- 
ward in  the  line  of  the  Internal  intermuscular  Septum  and  are 
inserted  as  a  single  band  into  the  internal  epicondyle. 

c.  M.  Coraco-epitrochlearis. 
Case : 

.? ,  Germany,  aet.  29.     January  11,  1894. 

Plate  XXXIX.     Left  upper  extremity. 

A  slender  superficial  tendon  arising  from  the  coracoid  process 
develops  a  thin  fusiform  muscle  at  about  the  middle  of  the  arm, 
which  passes  down  to  the  internal  epicondyle,  lying  upon  the 
brachial  vessels  and  the  large  nerves. 

The  obvious  connection  of  the  Coraco-epitrochlear  variations 
first  described  with  the  Coraco-brachialis  inferior  will  be  consid- 
ered in  dealing  with  the  relation  of  the  Biceps  to  that  muscle. 

3.  M.  Brachio-ulnaris  Medialis. 

Under  this  head  I  have  placed  the  variations  which  include  a 
third  bicipital  head,  arising  from  the  inner  surface  of  the  shaft 
of  the  humerus,  either  from  the  interval  between  the  Coraco- 
brachialis  and  Brachialis  anticus,  or  directly  from  the  latter 
muscle,  or  from  the  insertion  of  the  Coraco-brachialis  and  con- 
tinuous with  that  muscle. 

It  has  seemed  to  me,  in  examining  carefully  this  frequent  vari- 
ation, that  we  have  to  deal  here  with  a  Coraco-ulnar  head  which 
has  lost  its  girdle  attachment  and  has  transferred  its  origin  to 
the  shaft  of  the  humerus,  modifjing  its  insertion  b^- joining  the 
remainder  of  the  Biceps  muscle. 


1895.]  NEW   YORK   ACADEMY    OF    SCIENCES.  253 

The  relation  of  this  variation  to  the  Brachialis  anticus  and 
Coraco-brachialis  is  obvious  and  will  be  referred  to  below. 

In  the  above  series  I  have  encountered  this  third  internal 
head  in  the  following  instances  : 

1.  (?,  England,  aet.  73.     Januarj^  11,  1894. 
Left  upper  extremity. 

Internal  bicipital  head  derived  directly  from  the  humerus,  ex- 
ternal to  and  about  5  cm.  above  the  Coraco-brachialis  insertion, 
between  it  and  the  Brachialis  anticus,  completely  free  from  the 
latter  muscle. 

The  musculo-cutaneous  nerve,  after  pjercing  the  Coraco-bra- 
chialis, passes  between  the  additional  head  and  the  main  portion 
of  the  Biceps  muscle. 

2.  (?,  Ireland,  aet.  46.     January  11,  1894. 

Third  internal  bicipital  head  arising  from  the  outer  margin  of 
the  Coraco-brachialis  insertion,  and  in  close  connection  with  the 
superior  and  internal  origin  of  the  Brachialis  anticus. 

3.  S- ,  Ireland,  aet.  37.     October  17,  1893. 
Right  upper  extremity. 

Third  bicipital  head  arising  from  inner  surface  of  shaft  of  hu- 
merus at  the  Coraco-brachialis  insertion.  Separated  from  the 
main  Biceps  muscle  by  the  large  muscular  branches  of  the  mus- 
culo-cutaneous nerve,  which  perforates  the  Coraco-brachialis. 

The  internal  head  has  further  been  noted  in  the  following 
cases  : 

4.  $  ,  Ireland,  aet.  46.     January  24,  1894. 
Right  upper  extremity. 

5.  $,  Ireland,  aet.  62.     November  28,  1893. 
Right  upper  extremity. 

6.  ^,  Germany,  aet.  28.     October  5,  1893. 
Left  upper  extremity. 

Additional  head,  derived  in  this  instance  from  the  insertion  of 
the  Coraco-brachialis,  goes  mainly  into  the  semilunar  fascia. 

7.  9,  Germany,  aet.  84.     November  9,  1893. 
Left  upper  extremity. 

8.  9,  IJ.  S.,  white,  aet.  68.     November  22,  1893. 
Right  upper  extremity. 

Small  third  internal  head,  derived  chiefly  from  the  tendon  of 
of  the  Coraco-brachialis,  with  which  it  is  continuous. 

9.  ^  ,  Germany,  aet.  60.     December  14,  1893. 
Right  upper  extremity. 

10.  ^  ,  Bohemia,  aet.  30,     December  19,  1893. 
Left  upper  extremit3\ 

11.  $,  Italy,  aet.  40.     December  14,  1893. 
Right  upper  extremity. 


254  TRANSACTIONS   OF   THE  [MAY  13, 

II.  Relation  of  biceps  to  the  adjoining  deep  ventro-appendic- 

ULAR  fibres  of  THE  CORACO-BRACHIALIS,  AND,  III.  TO  THE 

DEEP  INTRINSIC  FLEXOR  OF  FOREARM,  BRACHIALIS 

ANTICUS. 

The  consideration  of  the  variations,  described  above  as  the 
Humero-ulnar  internal  head  and  the  Coraco-epitroehlear  slips,  in- 
dicate the  intimate  relation  existing  between  the  Biceps  and  the 
Brachialis  anticns  and  Coraco-brachialis. 

Hnmphry,*  in  describing  the  muscles  of  the  Cryptobranch, 
accentuates  the  close  relation  of  the  Coraco-brachialis  longus 
and  Biceps  of  this  animal.  He  finds  that  the  former  muscle 
divides  into  two  portions,  one  of  which  is  inserted  into  the 
ulnar  edge  of  the  humerus ;  the  other,  being  nearly  as  large,  is 
partly  inserted  into  the  side  of  the  long  tendon  of  the  Biceps, 
while  a  bundle  of  its  fibres  continues  over  the  elbow  and  is  in- 
serted into  the  ulna  near  the  joint.  Humphry  regards  this  lat- 
ter portion  as  the  representative  of  the  short  or  coracoid  bicip- 
ital origin  in  man. 

We  find  in  this  instance  on  the  one  hand  the  direct  union  of 
the  Coraco-brachialis  with  the  Biceps,  and  on  the  other  insertion 
of  part  of  the  muscle  into  the  ulna. 

Again  the  Brachialis  anticns  is  in  some  forms  (Pteropus) 
found  to  be  in  direct  continuity  with  the  Coraco-humeral,  f  and 
in  the  Seine  the  Biceps  derives  two  factors  from  the  humerus, 
which  occupy  the  position  of  the  Brachialis  anticns  and  are  so 
named  b3'  Riidinger.  Humphry  sums  the  mutual  relations  of 
these  three  muscles  up  as  follows  : 

"  They  show  the  Biceps  to  be  an  intermediate  between  the 
Coraco-humerals  and  Brachialis  anticus,  continuous  with  either 
or  both,  and  uniting  them  into  one  group,  extending  from  the 
coracoid,  along  the  ulnar  and  palmar  surface  of  the  humerus, 
to  the  radius  and  ulna." 

I  believe  that  we  may  properlv  regard  the  variations  of  the 
Biceps  above  referred  to  in  this  light.  Both  the  Coraco-epi- 
troehlear slips  and  the  Internal  humeral  heads  speak  for  the 
original  unity  of  a  muscular  plane  extending  between  coracoid 
and  ulna. 

The  separation  of  the  radius  as  the  rotatory-  element  of  the 
forearm  and  hand,  and  the  assignment  of  the  corresponding 
muscular  function  to  the  Biceps,  have  caused  the  elimination  of 
the  ulnar  segment  of  the  muscle,  leaving  the  Brachialis  anticus 
as  the  deep  intrinsic  flexor  connected  with  the  ulna,  and  reduc- 

♦  Op.  cit.,  p.  33. 

t  Humphry,  op.  cit.,  p.  164. 


1895.]  NEW   YORK   ACADEMY   OF   SCIENCES.  255 

ing  the  Coraco-brachialis  to  a  deep  ventro-appendicular  muscle 
confined  in  its  insertion  to  the  humerus. 

It  is  only  in  the  Third  Internal  humeral  head  of  the  Biceps, 
and  in  the  Coraco-epitrochlear  slips,  that  we  still  find  the  evi- 
dence of  the  original  connection  between  these  muscles,  and  see 
the  reversion  of  the  Biceps  toward  its  lost  ulnar  segment. 

It  is  onl}^  necessar}^  to  refer  in  this  connection  to  the  interest- 
ing account  of  the  structure  of  the  Coraco-brachialis  given  by 
Prof.  Wood,*  and  to  point  out  the  significance  of  the  occasional 
Coraco-brachialis  longus. 

Analysis  of  cases  of  Quadriceps  flexor  cubiti  and  evidences 
of  the  ulnar  tendency  of  the  Bicejys  in  variations  of  the  insertion. 

In  the  above  series  five  examples  of  a  four-headed  muscle 
have  been  encountered. 

1.  ^,  Ireland,  aet.  45.     January  9,  1894. 
Plate  XL.     Right  upper  extremity. 

A  third  additional  head  (gleno-ulnar)  arises  by  a  flat  tendon 
from  the  capsule  of  the  shoulder-joint,  between  the  long  and 
coracoid  heads.  It  is  separated  above  from  the  main  muscle  by 
the  muscuto-cutaneous  nerve,  after  the  latter  has  perforated  the 
Coraco-brachialis.  A  fourth  additional  head  (coraco-ulnar) 
arises  from  the  inner  surface  of  the  shaft  of  the  humerus,  almost 
directl}^  continuous  with  the  Coraco-brachialis  at  its  insertion, 
and  separated  from  the  Brachialis  anticus  b}^  a  branch  to  the  lat- 
ter muscle  from  the  musculo-cutaneous  nerve. 

The  left  upper  extremity  of  the  same  subject  presents  the  addi- 
tional internal  humeral  head  from  the  Coraco-brachial  insertion. 

The  case  affords  an  example  of  the  typical  composition  of  the 
four-headed  muscle.  The  gleno-ulnar  head  passes  to  the  deep 
and  ulnar  surface  of  the  main  muscle,  which  is  joined  lower  down 
by  the  coraco-ulnar,  the  continuity  of  the  latter  with  the  Coraco- 
brachialis  being  well  marked.  The  superficial  part  of  the  muscle 
is  constituted  by  the  large  gleno-  and  coraco-radial  heads. 

2.  9,  Ireland,  aet  40.     October  25,  1894. 

Plate  XLI.  Both  upper  extremities  present  the  same  ar- 
rangement. 

A  third  anomalous  head  arises  from  the  glenoid  margin  and 
capsule  of  the  shoulder,  passes  down  over  the  bicipital  groove, 
covering  the  tendon  of  the  long  head,  supplied  by  a  branch  from 
the  musculo-cutaneous  nerve,  after,  the  same  has  perforated  the 
Coraco-brachialis.  A  fourth  additional  head  arises  from  the 
humerus,  along  the  outer  margin  of  the  tendinous  Coraco-brach- 
ialis insertion. 

The  main  portion  of  the  musculo-cutaneous  nerve,  after  per- 

*  Journal  of  Anatomy  and  Physiology,  Vol.  I.,  p.  44,  1867. 


256  TRANSACTIONS   OF   THE  [MAY  13, 

fornting  the  Coraeo-brtichialis,  passes  first  between  the  3(1  and 
4th  additional  heads,  and  subse(iuently  turns  down  to  lie  be- 
tween the  accessory  heads,  a  short  distance  above  their  junction 
with  the  tendon  of  insertion,  and  the  BrachinMs  anticus. 

The  semilunar  fascia  is  well  developed,  scattered  fibres  ex- 
tending up  over  the  brachial  artery-  as  high  as  the  internal 
epicondyle. 

This  case  only  dirters  from  the  preceding  one  in  the  separa- 
tion of  the  fourth  accessory  head  from  the  Coraco-brachialis. 

3.  ^,  Germany,  aet.  62.  '  November  29,  1894. 
Plate  XLII.     Right  upper  extremity. 

A  combination  of  an  additional  gleno-ulnar  head  with  inter- 
mediate pectoral  tendon  attachment,  and  a  fourth  internal  hu- 
meral head,  arising  between  the  Coraco-brachialis  and  Brachialis 
anticus. 

The  insertion  is  peculiar.  The  radial  tendon  is  formed  b}-  the 
long  head  (gleno-radial)  and  by  the  deep  portion  of  the  coracoid 
and  additional  internal  humeral  heads  (coraco-radial).  The  re- 
maining superficial  portion  of  the  regular  coracoid  and  of  the 
internal  humeral  head  (coraco-ulnar)  is  joined  bj^  the  entire  ad- 
ditional glenoid  muscle  (gleno-ulnar)  and  passes  superficially 
inward  into  a  strong  tendinous  semilunar  fascia  which  is  well 
separated  from  the  radial  tendon. 

4.  J,  U.  S.  white,  aet.  G3.     November  7,  1894. 
Plate  XLII  I.     Right  upper  extremity. 

The  gleno-radial  and  gleno-ulnar  heads  are  well  defined  at 
their  origin,  fusing  before  meeting  the  coracoid  segment.  The 
4th  head  is  derived  from  the  outer  margin  of  the  regular 
coracoid  head  (coraco-radial?),  5  cm.  below  level  of  lesser 
tuberosity',  as  a  slender  slip,  about  10  cm.  long,  which  joins  the 
inner  margin  of  the  glenoid  portion,  before  the  latter  fuses  with 
the  main  coracoid  muscle. 

5.  9,  U.  S.  white,  aet.  26.     November  28, 1894. 
Plate  XLIY.     Left  upper  extremity'. 

A  third  internal  humeral  head  arises  from  the  shaft  of  the 
humerus  at  the  Coraco-brachialis  insertion  and  joins  the  regular 
coracoid  head  along  its  ulnar  margin,  2.5  cm.  above  the  level  of 
the  elbow.     (Coraco-radial  and  Coraco-ulnar). 

The  fourth  head  (gleno-ulnar)  is  derived  from  the  long  ten- 
don, along  its  outer  margin,  under  cover  of  the  Pectoralis,  b\-  a 
tendon  which  becomes  muscular  at  the  lower  border  of  the 
pectoral  tendon  and  fuses  about  the  middle  of  the  arm  with  the 
external  and  anterior  part  of  the  Brachialis  anticus. 

Macalister  *  has  fonnd  a  similar  slip  once. 

*  Op.  cit.,  p.  83. 


1895.]  NEW   YORK. ACADEMY   OF   SCIENCES.  257 

The  variation  is  interesting  as  affording  an  instance  of  con- 
tinuity of  the  Biceps  with  the  Brachialis  anticus,  and  hence  of 
a  direct  ulnar  destination  of  some  of  tlie  bicipital  glenoid  fibres. 

Variations  of  insertion  pointing  to  ulnar  attachment  of  Biceps. 

1.  ^,  Assyria,  aet.  28.     November  15,  1894. 
Plate  XLY.     Right  upper  extremity". 

A  muscular  belly,  entirely  separate  from  Brachialis  anticus, 
arises  from  the  lower  part  of  the  inner  margin  of  the  humeral 
shaft,  and  passes  downwards  and  outwards,  underneath  the  Bi- 
ceps, dividing  into  two  portions.  The  internal  division  passes 
to  reinforce  the  semilunar  fascia  ;  the  external  stronger  bundle 
dips  into  the  cubital  fossa  to  the  inner  side  of  the  radial  Biceps 
tendon,  joining  it,  and  giving  some  fibres  to  the  fascia  of  the 
Supinator  brevis.  The  additional  muscle  in  this  instance  is  e\i- 
dently  a  compound  of  portions  of  both  Coraco-radial  and  Coraco- 
ulnar,  whose  origin  has  shifted  downwards  to  the  humeral 
shaft,  the  proximal  portion  remaining  as  the  coraeoid  head  of 
the  regular  Biceps  and  the  Coraco-brachialis. 

The  compound  character  of  both  the  external  radial  tendon  of 
the  Biceps  and  of  the  semilunar  fascia  (internal  or  ulnar  tendon) 
is  well  shown  bj'  this  case. 

2.  $,  Ireland,  aet.  57.     October  7,  1893. 
Right  upper. 

Tendon  slip  from  radial  biceps  insertion  into  lesser  head  of 
Pronator  teres. 

3.  $  ,  Germany,  aet.  58.     January  23,  1894. 
Right  upper. 

Tendon  slip  from  radial  Biceps  tendon  into  Pronator  teres  and 
deep  fascia  of  forearm. 

Macalister  *  describes  insertions  of  the  Biceps  into  the  coro- 
noid  process,  Pronator  teres,  Coronoid  insertion  of  Brachialis 
anticus,  capsule  of  elbow  and  the  origin  of  some  of  the  flexor 
muscles. 

While  completing  this  paper  a  number  of  additional  bicipital 
variations,  bearing  out  the  views  expressed  relative  to  the  com- 
position of  the  muscle,  have  come  under  observation.  Among 
them  the  two  following  instances  illustrate  some  of  the  import- 
ant morphological  features  of  the  muscle  so  well  that  the}'  are 
added  to  this  paper.    - 

1.   ^ ,  Ireland,  aet.  67.     January  22,  1895. 

Plate  XLYI.     Left  upper  extremity. 

/.  Glenoid  Heads. 

The  outer  bicipital  head  (Gleno-radial)  is  well  developed.  In 
its  upper  portion  the  tendon  is  overlapped  by  a  distinct  band, 

*  Op.  cit,  p.  83. 


258  TRANSACTIONS   OF   THE  [MAY  18, 

arising  from  the  cai)sule  of  the  slioulder  joint  and  attached  to 
the  deep  surface  of  the  Pectoralis  major  tendon  (Capsulo-pec- 
toral  variety  of  Glono-ulnar  liead).  Ahout  4  cm.  above  the 
elbow  joint  a  slip  separates  from  the  inner  border  and  deep  sur- 
face of  the  main  muscle,  and,  becomini;  tendinous,  passes  down- 
ward and  inward  to  the  anterior  border  of  the  ulna,  just  below 
the  coracoid  insertion  of  the  Brachialis  anticus.  (Persistent  dis- 
tal portion  of  Gleno-ulnar  division). 

II.   Coracoid  Heads. 

A  broad  muscle,  arising  with  the  Coraco-brachialis  from  the 
coracoid  i)rocess,  divides  at  the  level  of  the  lower  Pectoralis 
margin  into  :  (a)  The  usual  short  or  coracoid  head,  which  passes 
down  and  out  and  joins  the  outer  head  a  little  above  the  middle 
of  the  arm  (^Coraco-radial  division'),  (b).  An  internal  muscle, 
completely  free  from  Coraco-brachialis,  which  immediately  sub- 
divides into  two  equal  portions.  Of  these  the  posterior  and  in- 
ternal muscle  descends  vertically  over  the  Coraco-brachialis  in- 
sertion, and  terminates  at  the  junction  of  middle  and  lower  one- 
third  of  the  arm  in  a  strong  tendon,  which  passes  down,  at  first 
free  and  subsequently  fused  with  Struther's  ligament,  to  the  in- 
ternal epicondyle.  {Goraco-epitrochUar  varietij  of  Gleno-ulnar 
head. 

The  anterior  muscle,  lying  upon  the  Brachialis  anticus  and  the 
internal  intermuscular  septum,  remains  completely  free  from 
surrounding  structures  and  terminates  in  a  strong  tendon  which 
passes  over  the  elbow  joint  and  is  inserted  into  the  coronoid 
process  of  the  ulna,  just  internal  to  the  Brachialis  anticus  inser- 
tion.    {Typical  Goraco-ulnar  head  of  muscle.) 

This  case  is  especially  important,  as  it  presents  not  only  the 
more  common  proximal  vestiges  of  the  obsolete  ulnar  divisions, 
but  also  exhibits  perfectly  the  rare  distal  or  insertion  portions, 
in  their  complete  form,  attached  to  the  ulna. 

The  separation  of  the  Biceps  insertion  from  the  ulna  and  the 
assignment  of  the  muscle,  as  a  supinator,  to  the  radius,  would 
lead  us  to  expect  this  disproportion,  as  regards  frequency  of  oc- 
currence, between  reversions  of  the  complete  distal  and  proxi- 
mal segments  of  the  lost  ulnar  division.  The  distal  or  inser- 
tion portion  of  the  ulnar  division  w^as  the  first  to  disappear  at 
the  insertion  into  the  ulna,  and  consequently  reverts  in  a  very 
much  smaller  percentage  in  its  complete  form  than  the  proxi- 
mal or  origin  portion,  whose  existence  has,  so  to  speak,  been 
prolonged  by  the  opportunit}'  of  uniting  with  the  radial  division. 

The  above  instance  exhibits  these  features  of  the  muscle-plan 
perfectly,  and  the  preparation  has  been  added  to  the  Variation- 
series  of  the  Morphological  Museum  of  Columbia  College. 


1895.]  NEW   YORK   ACADEMY   OF   SCIENCES.  259 

2.  The  second  case,  recently  observed,  which  presents  points 
of  especial  interest  in  connection  with  the  subject  of  this  paper, 
exhibits  one  of  the  important  relations  between  Biceps  and 
Brachialis  anticus,  and  emphasizes  the  significance  of  the  semi- 
lunar fascia,  as  representing  the  remains  of  an  ulnar  bicipital 
division  which  has  lost  its  skeletal  attachment,  in  accordance 
with  the  functional  specialization  of  the  muscle  as  the  main 
supinator  of  the  limb. 

$  ,  Ireland,  aet.  54.     March  15,  1895. 

Plate  XLVII.     Right  upper  extremity  : 

This  case  affords  a  well-marked  example  of  the  original  con- 
nection between  Biceps  and  Brachialis  anticus. 

The  origin  of  the  Biceps  in  this  arm  is  normal,  as  is  the  ar- 
rangement of  Coraco-brachialis.  A  strong  muscular  bundle 
separates  from  Brachialis  anticus  a  short  distance  below  the 
Coracobrachial  insertion.  The  outer  and  larger  portion  of  this 
muscle  joins  the  deep  surface  of  the  Biceps  and  passes  with  it 
to  the  radial  insertion.  The  inner  part  continues  downward 
and  inward,  gives  off  a  narrow  tendon  which  passes  with  the 
remainder  of  Brachialis  anticus  to  the  coronoid  process,  and 
then  expands  into  the  semilunar  fascia,  which  is  well  developed, 
crossing  obliquely  over  the  brachial  artery. 

The  additional  muscle  in  this  instance  is  evidently  an  Internal 
Brachio-ulnar  muscle,  which,  however,  presents  not  only  the 
usual  connection  with  the  radius  by  means  of  the  bicipital 
junction,  but  preserves  its  original  ulnar  insertion  both  by  the 
tendon  slip  to  the  coronoid  process  and  by  the  development  of 
the  entire  semilunar  fascia.  The  significence  of  the  latter 
structure,  entitling  it  to  be  considered  as  the  distal  portion  of 
an  ulnar  bicipital  segment  which  has  lost  its  skeletal  attachment, 
is  strongly  emphasized  by  the  arrangement  of  the  aberrant 
muscle  in  this  subject. 


PLATE   XVIII. 

Right  upper  extremity. 

9 ,  white,  U.  S.  aet.  62. 

Gleno-uhiar  head  ;  var.  1,  Capsulo-pectoral  teudon. 


Teans.  N.  Y.  Acad.  Sci. 


Vol.  XIV.,  PL.  XVIII. 


PLATE    XIX. 

Eight  shoulder  joint  of  same  subject,  opened  from  behind,  head  of  hu- 
morus  removed,  sho\ving  thickening  of  anterior  capsule  wall  by  the  Cap- 
sulo-pectoral  tendon. 


Tkans.  N.  Y.  Acad.  Sci. 


Vol.  XIV.,  PL.  XIX. 


^ 


H92 


Huntington 


Bigni.fir&anee— fyf  muRfiulaiL. 


variation. 


16 


<r 


.''ii'i'jwwf^Mv^^V^^" 


•'i-m.mfm 


jS^i^. 


PLATE     XX. 

Right  upper  extremity. 

<? ,  Austria,  aet.  ()5. 

Gleuo-uluar  head  ;  var.  1,  Capsulo-pectoral  teiulou. 


Teans.  N.  Y.  Acad.  Sci. 


Vol.  XI^^,  PL.  XX. 


PLATE    XXI. 

Eight  upper  extremity. 

9 ,  Gennany,  aet.  84. 

Gleno-uhiar  head,  var.  1,  Capsulo-pectoval  temlon. 


Teans.  N.  Y.  Acad.  Sci. 


Vol.  XIV.,  Pl.  XXI. 


V. 


:¥i  fij 


■-.,..;:  f»»^ 


PLATE    XXII. 

Eight  upper  extremity. 
$ ,  U.  S.  white,  aet.  24. 
Gleno-ulnar  head,  var.  "ia,  Gleuo-nlnar  muscle. 


Teans.  N.  Y.  Acad.  Sci. 


Vol.  XIV.,  Pl.  XXII. 


PLATE   XXIII. 

Right  upper  extremity. 
^,  U.  S.  -white,  aet.  50. 
Gleno-iilnar  liead,  var.  2a,  Gleno-ulnav  muscle. 


Teans.  N.  Y.  Acad.  Sci. 


Vol.  XIY.,  Pl.  XXIII. 


PLATE    XXIV. 

Right  upper  extremity. 
$ ,  r.  S.  negro,  aet.  50. 
Gleiio-uluar  head,  var.  2a,  Gleno-uhiar  muscle. 


Teans.  N.  y.  Acad.  Sci. 


Vol.  XIV.,  Pl.  XXIV. 


PLATE  XXV. 

Left  upper  extremity. 
9 ,  U.  S.  white,  aet.  23. 
Gleuo-ulnar  head,  var.  ■2a,  Gleno-ulnar  muscle. 


Teaks.  N.  Y.  Acad.  Sci. 


Vol.  XIV.,  Pl.   XXV. 


PLATE    XXVI. 

Left  upper  extremity. 

,y ,  U.  S.  negro,  aet.  50. 

Gleno-ulnar  head,  var.  "ib,  Gleno-nhiar  innscle. 


Teans.  N.  Y.  Acad.  Sci. 


Vol.  XIV.,  Pl.  XXVI. 


PLATE  XX  VII. 

Eight  upper  extremity. 

$,  Ireland,  aet.  3:2. 

Gleno-ulnar  head,  \a\\  2b,  Gleno-ulnar  muscle. 


Teaks.  N.  Y.  Acad.  Sci. 


Vol.  XI v.,  Pl.   XXVII. 


/■A-, 


PLATE    XXVIII. 

Left  upper  extremity'  of  preceding  subject. 

^ ,  Ireland,  aet.  32. 

Gleno-uluar,  head,  var.  2a,  Gleuo-ulnar  muscle. 


Teans.  N.  Y.  Acad.  Sci. 


Vol.  XIV.,  PL.  XXVIII. 


-^%, 


\y 


M^'V: 


PLATE   XXIX. 

Left  upper  extremity. 

$ ,  Ireland,  aet.  53. 

Gleuo-uhiar  head,  var.  2c,  transition  forms  and  variations. 


Teans.  N.  Y.  Acad.  Sci. 


Vol.  XIV.,  PL.  XXIX. 


PLATE    XXX. 

Left  upper  extremity. 

$ ,  Ireland,  act.  35. 

Gleno-ulnar  head,  var.  '2q,  transition  forms  and  variations. 


Teans.  N.  Y.  Acad.  Sci. 


Vol.  XIV.,  Pl.  XXX. 


/      / 


PLATE    XXXI. 

Right  upper  extremity. 

$,  Germany,  aet.  64. 

Gleno-ulnar  head,  var.  '2c,  transition  forms  and  variations. 


Tean-s.  N.  Y.  Acad.  Sci. 


Vol.  XIV.,  PL.  XXXI. 


PLATE  XXXII. 

Left  ui>i)er  extieniity. 
$ ,  Germany,  aet.  66. 
Gleuo-ulnar  head,  var.  3,  Gleno-epitroclilear  tendou. 


Trans.  N.  Y.  Acad.  Sci. 


Vol.  XIV.,  PL.    XXXII. 


m^l'**^ 


\ 


■N 


;'M/ 


PLATE   XXXIII. 

Left  upper  extremity. 

<? ,  Ireland,  aet.  42. 

Gleiio-ulnar  head,  var.  3,  Gleno-epitrochlear  tendon. 


Teans.  N.  Y.  Acad.  Sci. 


Vol.  XIV.,  PL.  XXXIII. 


PLATE  XXXIV. 

Right  upper  extremity. 

9,  Ireland,  aet.  27. 

Gleno-ulnar  heiid,  var.  4,  M.  Brachio-ulnaris  lateralis. 


Teaks.  N.  Y.  Acad.  Scr. 


Vol.  XIV.,  Pl.  XXXIV. 


I         5 


lliS'- 


PLATE  XXXV. 

•  Eifjht  upper  extremity. 
9 ,  U.  S.  negro,  aet.  34. 
Gleno-ulnar  lieiid,  var.  4,  'Si.  Braehio-uliuiris  lateralis. 


Teans.  N.  Y.  Acad.  Scr. 


Vol.  XIV.,  Pl.  XXXV. 


PLATK  XXXVI. 

Eifilit  upper  extremity. 
9,  Ireland,  aet.  72. 

Gleno-ulnar  head,  var.  6,  combination  of  tendinous  Gleno-ulnar  and  Cor- 
aco-epitroclilear. 


Trans.  N.  Y.  Acad.  Sci. 


Vol.  XIV.,  Pl.  XXXVI 


V 


PLATE  XXXVII. 

Riflht  upper  extremity. 
^,  U.  S.  ^vhite,  aet.  47. 
Coraco-ulnar  head,  var.  2a,  Coraco-epitrochlear  tendon. 


Teaks.  N.  Y.  Acad.  Sci. 


Vol.  XIV.,  Pl.  XXXVII. 


PLATE  XXXYIII. 

Eight  upper  extremitj'. 
^,  U.  S.  white,  aet.  46. 

Coraco-ulnar  head,  var.  2b,  Coraco-epi trochlear  and  Gleno-epitrochlear  ten- 
dons combined. 


Teans.  N.  Y.  Acad.  Sci. 


Vol.  XIV.,  Pl.  XXXVIII. 


PLATE  XXXIX. 

Left  upper  extremitv. 
S,  Gemiauy,  aet.  29. 
Coraco-uluar  liead,  -var.  2c,  M.  Coracorepitrochlearis. 


Teans.  N.  Y.  Acad.  Sci. 


Vol.  XIV.,  Pl.  XXXIX. 


TLATE   XL. 


Right  upper  extremity. 

$ ,  Ireland,  aet.  45. 

M.  Quadriceps  flexor  cubiti. 


Trans.  IST.  Y.  Acad.  Sci. 


Vol.   XIV.,  Pl.  XL. 


PLATE  XLI. 


Eight  upper  extremity. 

$ ,  Ireland,  aet.  40. 

]\I.  Quadriceps  flexor  cubiti. 


Teans.  N.  Y.  Acad.  Sct. 


Vol.  XIV.,  Pl.  XLI. 


PLATE  XLII. 


Right  upper  extremity. 

$  ,  Germany,  aet.  62. 

M.  Quadriceps  flexor  cubiti. 


Teans.  N.  Y.  Acad.  Sct. 


Vol.  XIV.,  PL.  XLH. 


C 


PLATE   XLIII. 


Right  upper  extremity. 
$ ,  U.  S.  white,  aet.  63. 
M.  Quadriceps  flexor  cubiti. 


Teans.  N.  Y.  Acad.  Sci. 


Vol.  XIV.,  Pl.  XLIII. 


PLATE  XLIV. 


Left  upper  extremity. 
9 ,  U.  S.  white,  aet.  26. 
M.  Quatlriceps  flexor  cubiti. 


Tbaks.  N.  Y.  Acad,  Sci. 


Vol.  XJV.,  Pl.  XLIV. 


PLATE  XLV. 

Right  upper  extremity. 

S,  Assyria,  aet.  28. 

M.  Brachialis  accessorius,  joining  insertion  of  Biceps. 


Teans.  N.  Y.  Acad.  Sci. 


Vol.  XIV.,  PL.  XLV. 


PLATE    XLVI. 

Left  upper  extremity. 
S,  Ireland,  aet.  67. 

Gleno-uluar  and  Coraco-uluar  muscles,  complete  form,  with  distal  por- 
tions persistent. 


Teaks.  N.  Y.  Acad.  Sci. 


Vol.  XIV.,  Pl.  XLVI. 


PLATE    XLVII. 

Right  upper  extremity. 
9 ,  Ireland,  aet.  54. 

Connection  of  Biceps  and  Brachialis  anticus,  with  complete  derivation  of 
semilunar  fascia  from  the  latter  muscle. 


Trans.  N.  Y.  Acad.  Sot. 


Vol.  XIV.,  Pl.  XLVII. 


I 


